zipkin2.internal.DependencyLinker Maven / Gradle / Ivy
/*
* Copyright The OpenZipkin Authors
* SPDX-License-Identifier: Apache-2.0
*/
package zipkin2.internal;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Logger;
import zipkin2.DependencyLink;
import zipkin2.Span;
import zipkin2.Span.Kind;
import static java.util.logging.Level.FINE;
/**
* This parses a span tree into dependency links used by Web UI. Ex. http://zipkin/dependency
*
* This implementation traverses the tree, and only creates links between {@link Kind#SERVER
* server} spans. One exception is at the bottom of the trace tree. {@link Kind#CLIENT client} spans
* that record their {@link Span#remoteEndpoint()} are included, as this accounts for uninstrumented
* services. Spans with {@link Span#kind()} unset, but {@link Span#remoteEndpoint()} set are treated
* the same as client spans.
*/
public final class DependencyLinker {
final Logger logger;
final SpanNode.Builder builder;
final Map callCounts = new LinkedHashMap<>();
final Map errorCounts = new LinkedHashMap<>();
public DependencyLinker() {
this(Logger.getLogger(DependencyLinker.class.getName()));
}
DependencyLinker(Logger logger) {
this.logger = logger;
this.builder = SpanNode.newBuilder(logger);
}
/** All {@code spans} must have the same trace id. */
public DependencyLinker putTrace(List spans) {
if (spans.isEmpty()) return this;
SpanNode traceTree = builder.build(spans);
if (logger.isLoggable(FINE)) logger.fine("traversing trace tree, breadth-first");
for (Iterator i = traceTree.traverse(); i.hasNext(); ) {
SpanNode current = i.next();
Span currentSpan = current.span();
if (logger.isLoggable(FINE)) {
logger.fine("processing " + currentSpan);
}
Kind kind = currentSpan.kind();
// When processing links to a client span, we prefer the server's name. If we have no child
// spans, we proceed to use the name the client chose.
if (Kind.CLIENT.equals(kind) && !current.children().isEmpty()) {
continue;
}
String serviceName = currentSpan.localServiceName();
String remoteServiceName = currentSpan.remoteServiceName();
if (kind == null) {
// Treat unknown type of span as a client span if we know both sides
if (serviceName != null && remoteServiceName != null) {
kind = Kind.CLIENT;
} else {
logger.fine("non remote span; skipping");
continue;
}
}
String child;
String parent;
switch (kind) {
case SERVER:
case CONSUMER:
child = serviceName;
parent = remoteServiceName;
if (current == traceTree) { // we are the root-most span.
if (parent == null) {
logger.fine("root's client is unknown; skipping");
continue;
}
}
break;
case CLIENT:
case PRODUCER:
parent = serviceName;
child = remoteServiceName;
break;
default:
logger.fine("unknown kind; skipping");
continue;
}
boolean isError = currentSpan.tags().containsKey("error");
if (kind == Kind.PRODUCER || kind == Kind.CONSUMER) {
if (parent == null || child == null) {
logger.fine("cannot link messaging span to its broker; skipping");
} else {
addLink(parent, child, isError);
}
continue;
}
// Local spans may be between the current node and its remote parent
Span remoteAncestor = firstRemoteAncestor(current);
String remoteAncestorName;
if (remoteAncestor != null
&& (remoteAncestorName = remoteAncestor.localServiceName()) != null) {
// Some users accidentally put the remote service name on client annotations.
// Check for this and backfill a link from the nearest remote to that service as necessary.
if (kind == Kind.CLIENT && serviceName != null && !remoteAncestorName.equals(serviceName)) {
logger.fine("detected missing link to client span");
addLink(remoteAncestorName, serviceName, false); // we don't know if there's an error here
}
if (kind == Kind.SERVER || parent == null) parent = remoteAncestorName;
// When an RPC is split between spans, we skip the child (server side). If our parent is a
// client, we need to check it for errors.
if (!isError && Kind.CLIENT.equals(remoteAncestor.kind()) &&
currentSpan.parentId() != null && currentSpan.parentId().equals(remoteAncestor.id())) {
isError = remoteAncestor.tags().containsKey("error");
}
}
if (parent == null || child == null) {
logger.fine("cannot find remote ancestor; skipping");
continue;
}
addLink(parent, child, isError);
}
return this;
}
Span firstRemoteAncestor(SpanNode current) {
SpanNode ancestor = current.parent();
while (ancestor != null) {
Span maybeRemote = ancestor.span();
if (maybeRemote != null && maybeRemote.kind() != null) {
if (logger.isLoggable(FINE)) logger.fine("found remote ancestor " + maybeRemote);
return maybeRemote;
}
ancestor = ancestor.parent();
}
return null;
}
void addLink(String parent, String child, boolean isError) {
if (logger.isLoggable(FINE)) {
logger.fine("incrementing " + (isError ? "error " : "") + "link " + parent + " -> " + child);
}
Pair key = new Pair(parent, child);
if (callCounts.containsKey(key)) {
callCounts.put(key, callCounts.get(key) + 1);
} else {
callCounts.put(key, 1L);
}
if (!isError) return;
if (errorCounts.containsKey(key)) {
errorCounts.put(key, errorCounts.get(key) + 1);
} else {
errorCounts.put(key, 1L);
}
}
public List link() {
return link(callCounts, errorCounts);
}
/** links are merged by mapping to parent/child and summing corresponding links */
public static List merge(Iterable in) {
Map callCounts = new LinkedHashMap<>();
Map errorCounts = new LinkedHashMap<>();
for (DependencyLink link : in) {
Pair parentChild = new Pair(link.parent(), link.child());
long callCount = callCounts.getOrDefault(parentChild, 0L);
callCount += link.callCount();
callCounts.put(parentChild, callCount);
long errorCount = errorCounts.containsKey(parentChild) ? errorCounts.get(parentChild) : 0L;
errorCount += link.errorCount();
errorCounts.put(parentChild, errorCount);
}
return link(callCounts, errorCounts);
}
static List link(Map callCounts,
Map errorCounts) {
List result = new ArrayList<>(callCounts.size());
for (Map.Entry entry : callCounts.entrySet()) {
Pair parentChild = entry.getKey();
result.add(DependencyLink.newBuilder()
.parent(parentChild.left)
.child(parentChild.right)
.callCount(entry.getValue())
.errorCount(errorCounts.getOrDefault(parentChild, 0L))
.build());
}
return result;
}
static final class Pair {
final String left, right;
Pair(String left, String right) {
this.left = left;
this.right = right;
}
@Override
public boolean equals(Object o) {
if (o == this) return true;
if (!(o instanceof Pair)) return false;
Pair that = (DependencyLinker.Pair) o;
return left.equals(that.left) && right.equals(that.right);
}
@Override
public int hashCode() {
int h$ = 1;
h$ *= 1000003;
h$ ^= left.hashCode();
h$ *= 1000003;
h$ ^= right.hashCode();
return h$;
}
}
}